Door operating mechanism



Sept. 7,1937. E. R. GREER ET AL DOOR OPERATING MECHANISM Filed June 27', 1956 4 Sheets-Sheet l Filed June 27, 1936 4 Sheets-Sheet 2 Zinnentors Sept. 7-, 1937. E. R. GREER ET AL DOOR OPERATING MECHANISM 4 Sheets-Sheet 3 Filed June 27, 1956 s r m e D n 3 Sept. 7, 1937. E. R. GREER ET AL 2,092,309

' DOOR OPERATING MECHANISM Filed June 27, 1956 4 sheets-sheet 4 Patented Sept. 7, 1937 UNITED STATES PATENT OFFICE DOOR OPERATING MECHANISM tion of Delaware Application June 27, 1936, Serial No. 87,614

1'7 Claims.

The invention relates to dump wagons and is concerned more specifically with a mechanism for operating the doors of such vehicles, particularly bottom dump doors. Subject matter disclosed but not specifically claimed herein is claimed in a copending application filed contemporaneously herewith by E. R. Greer, Door operating mechanism.

When a bottom dump wagon arrives at the dump it usually does not stop for dumping but the doors are unlocked while the vehicle is in progress, the doors fly open, and substantially the whole load drops out of the wagon box all at once. Although the wagon may be drawn at a good rate of speed the load, due to the sudden discharge, is hardly scattered and the pile of ma terial which has been dumped is quickly cleared by the wagon. In other words, the time during which the doors must be open, is very short, and the doors may be closed almost immediately after they have swung into fully open position.

It is an object of the invention to provide a power actuated door operating mechanism which, in normal operation, functions to unlock the doors, then leaves the doors unaffected for a short length of time during which they may swing into fully open position without restraint and during which time the whole load may drop out of the wagon box and the vehicle be drawn clear of the pile of material which has been dumped, and which then automatically starts closing the doors by power. With such a mechanism the doors will not be subject to closing power while the load is being dumped and while the vehicle is being drawn clear of the pile of material which has been dumped, but the doors will automatically begin to close under power after the vehicle has cleared the pile of material which has been dumped.

A further object of the invention is to provide a power actuated door operating mechanism which has an initial idling movement and a subsequent power movement, and which permits the doors to swing into fully open position without restraint during the idling movement and to remain open until the beginning of the power movement which causes them to close. The idling period of the mechanism is preferably made somewhat longer than the short time interval which occurs between the moment at which the doors are unlocked and the moment at which the vehicle, when drawn at normal speed, clears the pile of material which has been dumped. A mechanism having an initial idling period as stated, may be connected to its source of power and started to operate shortly before the doors are unlocked, and by the time the mechanism becomes effective to close the doors, the doors have swung into fully open position, the load has dropped out of the wagon box, and the vehicle has been drawn clear of the pile of material which has been dumped. The idling period may be made shorter or longer but it should at least be long enough to afford sufficient time during which the doors may swing into fully open position, during which the load may drop out of the wagon box, and during which the vehicle may be drawn clear of the pile of material which has been dumped.

Another object of the invention is to provide a power actuated door operating mechanism which has an initial idling movement and a subsequent power movement; in which a first part of the initial idling movement causes unlocking of the doors; in which the doors may swing into fully open position without restraint and stay open' during the remaining part of the idling movement; and in which the subsequent power movement closes the doors.

Another object of the invention is to provide a door operating mechanism in which an initial movement of a power actuated element causes unlocking of the doors; in which the doors may swing into fully open position without restraint and stay open for a short length of time while the power actuated element continues its movement, and in which the power actuated element by its still further continued movement finally causes closing of the doors.

A further object of the invention is to provide a door operating mechanism in which a power actuated element, by an initial movement, causes unlocking of the doors; in which the doors may swing into fully open position while the power actuated element continues its movement; in which the power actuated element, by its further continued movement, automatically causes closing of the doors after they have remained open long enough to permit the load to drop out of the wagon box and the vehicle to be drawn clear of the load which has been dumped; and in which the automatic closing of the doors may be prevented and the doors kept open at will for any length of time.

A further object of the invention is to provide a door operating mechanism which is operable by the selective application and release of fluid pressure to open and reclose the doors of a dump wagon, so that only a single hose connection is necessary between a source of fluid pressure on the tractor which pulls the wagon and the door operating mechanism on the wagon.

A still further object of the invention is to provide a power actuated door operating mechanism, which is simple and compact in construction, efficient in operation, and which may be manufactured at low costs.

These and other objects and advantages of the invention will be apparent from the following description. A clear conception of an embodiment of the invention and of the operation of a device constructed in accordance therewith, may be had by referring to the drawings accompanying and forming a part of this specification in which like reference characters designate the same or similar parts in the various views:

Fig. 1 is a side View of a cart type bottom dump wagon hitched to a tractor;

Fig. 2 is a detail view of a winding shaft for closing the doors of the bottom dump Wagon shown in Fig. 1;

Fig. 3 is a rear view of the door winding mechanism at the rear of the bottom dump wagon shown in Fig. 1;

Fig. 4 is a side view of the mechanism shown in Fig. 3;

Fig. 5 is a section on line V-V of Fig. 3, showing the mechanism in a position different from the position in which it is shown in Fig. 4;

Fig. 6 is a section on line VIVI of Fig. 3, showing the mechanism in the same position in which it is shown in Fig. 5; and

Fig. '7 is a diagrammatic view of a hydraulic power system in connection with the winding mechanism shown in Fig. 3.

The bottom dump wagon shown in Fig. 1 has a pair of bottom dump doors I which may be pulled up into closed position by chains 2 secured to the doors and guided over pulleys 3 mounted in the side walls of the wagon box. The wagon is hitched to a tractor 4, of which only the rear end is shown in Fig. 1, a drivers seat on the tractor being indicated by the reference character 5. The tractor and the wagon are flexibly connected by a universal hitch 6, so that the tractor and the wagon may move relative to each other when the vehicle train is driven through a curve or over rough ground. The wagon has a substantially rectangular bottom frame I on which the wagon box 9 is mormted and on which the bottom dump doors I are hinged by means of suitable hangers 8, the wagon box being open at the top and at the bottom and having a transverse rear wall H]. A winding shaft II is mounted on the wagon box 9 by means of journal bearings l2 and 13 (Fig. 2) which are secured to the outer side of the rear wall ll] of the Wagon box. The chains 2 are connected with the winding shaft by chain portions I4 which are secured to sheaves 5 and I6 mounted on the ends of the winding shaft, as shown in Fig. 2, and on which the chain portions i4 may be wound up by rotation of the winding shaft II for the purpose of closing the doors.

Mounted on the shaft II by means of bearings 56 is a frame l1, comprising side plates l8 and IS, an angle iron connecting the side plates at their lower ends, and an angle iron 2| connecting the side plates between their upper and lower ends. The bearings 56 are secured to the side plates l8 and I9, and the frame I! is prevented from swinging about the shaft H by a lug 22 which extends laterally from the side plate I9 and is bolted to the wagon box. Mounted on the frame I"! isa' hydraulic cylinder 23which is secured at its lower end to the angle iron 20 in the middle between the side plates l8 and IS. A piston rod 24 extends through the upper end of the hydraulic cylinder and is connected at its lower end to a piston 23' within the cylinder 23. The upper end of the piston rod 24 is connected to a cross head 25 which is guided between the side plates l8 and i9 and between guides 26 and 26 secured to the inner sides of the side plates 18 and 19. A pair of coil springs 21 urge the cross head upwardly and normally hold it in its highest position, that is, in the position in which the piston in the cylinder 23 is at the upper end of its stroke, heads at the upper ends of rods being relied upon as a stop, the rods being adjustably secured at their lower ends to the angle iron 20 and having sliding engagement with the cross head 25. The coil springs are held in place by telescoping tubes 28 and 29, the tubes 28 being secured to the angle iron 28 and the tubes 29 to the cross head 25. A. link chain 36 connects the cross head 25 with the winding shaft ll, one end of the link chain being secured to the cross head as shown in Fig. l, and the other end of the chain being secured to a sleeve (H with suitable fastening cars 32, the sleeve being rigidly secured to the shaft H, see Fig. 2.

The sheaves l5 and It on the winding shaft I! have sufficiently large diameters so that rotation of the shaft ll through an angle of about 250 in one direction will cause full opening of the doors, and so that rotation of the shaft Ii through the same angle in the opposite direction will cause complete closing of the doors from their fully open position. In Fig. 6 the sleeve 3| and the fastening ears 32 thereon are shown in the position which they occupy when the doors are fully open; that is, in the position of the sleeve 3| and ears 32, as shown in Fig. 6, the shaft H is in a rotated position in which the chains M are unwound from the sheaves l5 and I5 and from which position the shaft Ii must be rotated in anti-clockwise direction, with reference to Fig. 6, through an angle of about 250 in order to close the doors completely. Such rotation is imparted to the shaft H through the link chain 30 by a descent of the cross head 25 in the frame H. In order to cause a downward movement of the cross head, fluid under pressure, preferably oil, is admitted into the cylinder 23 above the piston therein as at 33, and when the piston reaches the lower end of its stroke the sleeve 3! and fastening cars 32 thereon are in the position shown in Fig. 4, which is the position which the sleeve and ears occupy when the doors are completely closed. After the shaft has been rotated through an angle of about 250 in order to close the doors, reverse rotation thereof is prevented by a ratchet gear described more fully hereinbelow, the oil pressure above the piston in the cylinder is released and the cross head returns into its highest position under the pressure of the coil springs 21. The chain 30 is then slack as shown in Fig. 4, and rests on a shelf 34, the shelf being secured to the cross head 25 in any suitable manner. Instead of letting the slack chain rest on a shelf, as shown, a spring pressed roller may be employed to pull the slack chain away from the shaft II and from the cross head 25 into a position substantially as shown in Fig. 4, the purpose being merely to prevent the slack chain from becoming entangled in the mechanism.

The ratchet gear for holding the shaft ll against reverse rotation after the doors have been closed, is shown at the right of Fig. 3. It

screw 42.

comprises a ratchet wheel 35 which is keyed on the shaft II, and a pawl 36 supported by a pair of arms 31. The arms 31 are rigidly secured to a long sleeve 38 which is rotatably supported on a pin 39, the pin being mounted at one end in an upward extension of the side plate I8 of the frame 11, and at the other end in a plate 48 pivotally supported on the shaft l l and connected at its lower end to the side plate 19 of the frame 11 by a cross plate 41. The cross plate 41 carries an adjustable stop, in the form of a set screw 42, for the pawl supporting arms 31, the latter being connected at their lower ends by a cross piece 43 which engages the end of the set screw 42. A spring 44 connected at one end to the side plate 19 of the frame l1 and at the other end to one of the arms 31, draws the cross piece 43 against the set screw 42. The pawl 38 is pivotally mounted between the arms 31 on a pin 45 and has a depending weighted portion so as to be urged by gravity into engagement with the teeth of the ratchet wheel 35. The portions of the arms 31 between the pins 39 and 45, the pins and the pawl, constitute a toggle relationship which may be adjusted by the set screw 42.

The ratchet wheel is unlocked by swinging the arms 31 outwardly, that is, away from the set For this purpose the sleeve 38 carries two bell crank levers 46 and 41 which are rigidly secured to the sleeve at opposite sides of a central vertical plane through the cylinder 23. Fig. 4 shows the bell crank lever 41 in the position which it occupies when the cross piece 43 of the pawl supporting arms 31 engages the set screw 42, and in that position the upper arm of the bell crank lever extends substantially horizontally from the sleeve 38 and over the shaft 1 I, while the lower arm extends downwardly and outwardly towards the wall of the wagon box on which the mechanism is mounted. The other bell crank lever 46 is similarly positioned on the sleeve 38, and the ends of the lower arms of both bell crank levers are connected by an angle iron cross piece 48, one flange of the angle iron extending downwardly and rearwardly as shown in Fig. 6. The upper arms of the bell crank levers are connected at their ends by a pin 59 on which two L-shaped trigger arms 49 are pivotally mounted by means of a sleeve 50', as more clearly shown in Fig. 3. The trigger arms 49 are connected at their lower ends by a cross member 5|, and, near the angle of the L; by a platelike cross member 51 which is not only a reinforcing element but primarily an abutment which may be struck by the lugs 32 and the chain 30 when the shaft ll rotates in clockwise direction, with reference to Fig. 4, the purpose being to swing the trigger arms 49 from the position in which they are shown in Fig. 4 into the position in which they are shown in Fig. 6. A cross pin 58 extending through the trigger arms 49 near their lower ends projects laterally therefrom and engages the guides 26 to limit swinging movement of the trigger arms about the axis of pin 58 in clockwise direction, with reference to Fig. 4. When the cross pin 58 engages the guides 26' the cross member 5| of the trigger arms projects into the path of the cross head 25, as shown in Fig. 4 and the upper legs of the trigger arms are kept spaced from the shaft ll so that when the cross head 25 strikes the cross member 5|, the trigger arms may move with the cross head in a downward direction at least for a limited length of travel. Pivotally secured to another cross pin 59 between the trigger arms 49 is a bolt 53 which extends slidably through the downwardly and rearwardly extending flange of the cross member 48 between the bell crank levers 46 and 41, and which carries at its outer end a pair of nuts 68, one nut serving as a jam nut for the other. The nut 68 closest to the downwardly and rearwardly extending flange of the cross piece 48 is so adjusted on the bolt 53 as to provide for some clearance between said nut and the flange, while the mechanism is in. the position in which itis shown in Fig. 4. When the cross head 25 moves downward in what may be called an advance direction, it strikes the cross member 5 of the trigger arms and pulls downwardly on the trigger arms, causing the bell crank levers 46 and 41 to pivot on the axis of pin 39. The mentioned clearance between the first nut 89 and the cross piece 48 permits limited pivotal movement of the bell crank levers while the cross member 51 remains engaged with the cross head 25. The limited pivotal movement of the bell crank levers about the axis of pin 39 is transmitted through the tube 38 to the pawl carrying arms 31, causing the pawl 36 to kick over center and consequent release of the ratchet wheel 35. Under the weight of the doors 1 and the load resting thereon, if the wagon is loaded, the shaft will then spin around rapidly in clockwise direction, with reference to Fig. 4, and the lugs 32 will strike against the abutment 51, causing the cross member 51 to be pulled out of engagement with the cross head 25 and thus clearing the path of the latter for continued downward movement. A tubular spacer 51 (Fig. 6) and a light compres sion coil spring 52 are arranged on the bolt 53 in the space between the downwardly and rearwardly extending flange of the cross piece 48 and the cross pin 59. When the cross member 51 on the trigger arms is struck by the lugs 32 the ensuing movement of the trigger arms first compresses the coil spring 52 and then positively pushes the bell crank levers 46 and 41 about the axis of pin 39 in anti-clockwise direction with reference to Fig. 6, due to contact of the tubular spacer 61 with the downwardly and rearwardly extending flange of the cross piece 48. The positive movement of the bell crank levers 4-5 and 41 by the tubular spacer 61 causes the pawl 38 to be moved still further away from the ratchet wheel 35, as shown in Fig. 5. The cross member 51 rides on the chain 33 and the pawl will there fore remain in the position relative to the ratchet wheel 35 as shown in Fig. 5 until the shaft H is rotated in anti-clockwise direction, with reference to Fig. 6, far enough to permit the trigger arms 49 to fall back into the position shown in Fig. 4, where the pin 58 engages the guides 26'; the pawl 36 will then again be in the position relative to the ratchet wheel 35, in which it is shown in Fig. 4.

Referring to Fig. '7, a fluid reservoir is indicated by 62, the reservoir being mounted on the tractor as shown in Fig. l. Mounted within the reservoir 52 is a pump 53 having a drive shaft with a belt pulley 84 secured thereto at the outside of the reservoir. A belt 65 trained over the pulley 64 is driven by a constantly revolving shaft 66 on the tractor, as generally'indicated in Fig. 1. The pump 53 has an intake opening 81 in communication with the interior of the reservoir 82, and a discharge opening 68 in communication with a conduit 89 leading out of the reservoir. The conduit 69 is connected through a hose 10 with the inlet opening 1! of a control valve generally indicated by 12. The valve hastwo outlet openings, an upper one 13 which communicates with the reservoir 62 through a conduit 14, and a lower one '15 which communicates with the cylinder 23 through a conduit 16. The body of the valve '12 is divided by a partition 11 into two compart ments, a left one in communication with the inlet opening 7|, and a right one in communication with the outlet opening 13. Communication between the right and the left compartments is controlled by a cylinder element M which is rotatable in the valve body and which communicates at its left open end with the left compartment of the valve body. Rotation of the cylinder 18 by means of the handle 19 brings an opening 88 of the cylinder into more or less registering relation with an opening 8| in the partition 17, and when the handle is rotated into one extreme position the opening 8| is fully open and when the handle is rotated into. another extreme position the opening 8| is fully closed. An opening 82 in the partition 11 is normally closed by a spring pressed plunger 83, but upon excessive pressure in the left compartment the plunger 83 permits escape of fluid from the left to the right compartment through the opening 82. The left compartment communicates directly with the outlet opening I5 of the valve body, as shown in Fig. 7. A gate valve 85 is arranged in the conduit 16, and by closing the gate valve 85, the hydraulic cylinder 23 may be put out of commission, if desired.

The operation of the mechanism is as follows: Assuming that the mechanism is in the position shown in Fig. 4, the chains M are wound up on the sheaves 5 and I6, and the doors are closed, as stated hereinbefore; the cross piece 63 of the pawl supporting arms 31 engages the set screw 42, and the pawl 36 engages the ratchet wheel 35, preventing the latter from turning under the torque which acts upon the shaft through the chains M, the chains being under tension due to the weight of the doors and due to the load of material thereon if the wagon box is loaded. The ratchet gear constitutes the only means for holding the doors closed, there being no other locks or latches for holding the doors closed. When the wagon arrives at the dump the operator, without stopping the vehicle, turns the handle 79 of the valve 72 into the extreme position in which the opening 8| is fully closed, and the entire fluid discharge of the pump 63 will then be forced into the cylinder 23 above the piston therein, as will be clear from Fig. '7. Under the fluid pressure acting upon the piston the cross head 25 begins to descend and strikes the cross member 5| of the trigger arms 49, as will be apparent from Fig. 4. As the cross head continues its downward m0vement, downward pull is exerted upon the trigger arms 49, and as a result the bell crank levers 46 and 41 will be rotated about the axis of pin 39. The rotation of the bell crank levers is transmitted to the pawl supporting arms 31 through the sleeve 38, and the arms 31 are swung outwardly and carry the pawl supporting pin 45 over the center of the toggle, at which moment the pawl kicks over and the doors fly open, causing the shaft II and ratchet Wheel 35 to spin around at great speed, in clockwise direction with reference to Fig. 4. The downward movement of the cross head 25 up to the moment when the doors fly open is comparatively short, and when the pawl 36 kicks over most of the chain 30 is still slack. The ensuing rapid rotation of shaft II and sleeve 3| however, winds up most of the slack chain 3|, and at the moment the doors reach. their fully openposition there will still be and the vehicle is drawn clear of the pile of material which has been dumped. Depending on the rapidity with which the pressure fluid is forced into the cylinder 23 more or less time is required to take up the remaining slack of the chain 38,

and more or less time will be afforded for drawing the vehicle clear of the pile of material which has been dumped. The present tendency in dirt moving operations is towards high speeds; the wagons are drawn by high speed tractors, and as the wagons do not stop or even slow down for dumping, very little time is necessary to clear the dumped load. Consequently, in the present mechanism the chain 38 may almost become tight when it is wound up on the sleeve 28 by the rotation of shaft after the cross head 25 has struck the cross member 5|. At any rate, the continued downward movement of the cross head 25 will eventually exert a heavy pull on the chain 30, and under this pull the doors will be closed as has been explained hereinbefore. During the last part of the downward movement of the cross head 25 the bell crank levers 46 and 41 return into their normal position which is shown in Fig. l, as has been explained hereinbefore, the pawl 86 is moved against the ratchet wheel 25, and during the last part of the closing movement of the doors the pawl rides over the teeth of the ratchet Wheel. When the piston in cylinder 23 has reached the lower end of its stroke rotation of shaft stops, and the pawl locks the doors in closed position. It is then necessary to release the pressure of the fluid above the piston 23' in cylinder 23 to permit the springs 21 to return the cross head into its highest position as shown in Fig. 4. In order to release the fluid pressure above piston 23 the operator turns the handle 79 of the valve T2 into the extreme position in which the opening BI is fully open. The entire fluid above piston 23 is then returned into the reservoir under the action of springs 21, there being practically no pressure set up by the pump because its discharge is then directly connected with the reservoir through the open passage 8|. During its return or upward movement the cross head 25 strikes the cross member 5| again, but this time nothing happens except that the cross member 5| is forced out of the way of the cross head against the pressure of spring 52, the cross member 5| sliding back under the cross head 25 as soon as it has been cleared by the latter.

While the piston in the cylinder 23 moves down under fluid pressure, air is forced out of the cylinder from below the piston through a vent 54, and while the piston moves up under the action of springs 21, air is drawn into the cylinder through said vent.

If it is desired to hold the doors open for a longer time than is afforded by the automatic functioning of the mechanism, this may easily be done by rotating the handle 19 from the extreme position in which the passage 8| is fully closed into the other extreme position in which the passage 8| is fully open as soon as the ratchet gear has been tripped by the initial downward movement of the cross head 25, and before the cross head begins to rotate the shaft II by pulling on the chain 30. Due to the opening of passage 8| the cross head will return to its'highest position, and if it is later desired to close thedoors, the passage 81 is again closed and kept closed long enough to force enough fluid into the cylinder 23 to bring the piston 23 down to the lower end of its stroke. The first part of the downward movement of the cross head up to the time when rotation of the shaft l I is started by pull on the chain 30, is the idling movement of the mechanism, referred to hereinbefore in the statement of invention, and .the part of the downward movement of the cross head which causes rotation of the shaft, 1 I by pull on the chain 30, is the power movement.

It should be understood that it is not intended to limit the invention to the exact details of construction herein described, for various modifications within the scope of the claims may occur to persons skilled in the art.

We claim: 1. In a door operating mechanism, a reciprocable drive element, lost motion connecting means operable by said drive element to effect closing of the doors by movement of said drive element in an advance direction and adapted to permit unrestrained opening of the doors after return of said drive element by reverse movement hereof to its starting position, means effecting said return movement of said drive element independently of movement of the doors, means for releasably locking the doors in closed position, and actuating means for said locking means operable by said drive element to release said looking means by an initial movement of said drive element in said advance direction and adapted to prevent release of said locking means by said reverse movement of said drive element.

2. In a door operating mechanism, a reciprocable drive element, lost motion connecting means operable by said drive element to effect closing of the doors by movement of said drive element in an advance direction and adapted to permit unrestrained opening of the doors after return of said drive element by reverse movement thereof to its starting position, power storage means adapted to be charged by movement of said drive element in said advance direction and to effect said reverse movement of said drive elementindependently of movement of the doors, means for releasably locking, the doors in closed position, and actuating means for said locking means, operable by said drive element to release said locking means by an initial movement of said drive element in said advance direction and adapted to prevent release of said locking means by said reverse movement ofsaid drive element.

3. In a door operating mechanism, a rotatable door actuatingshaft, ratchet means for locking said shaft against door opening rotation, a reciprocable drive element operatively connected with said shaft by lost motion connecting means adapted to transmit advance movement of said drive element to said shaft for causing door closing rotation thereof, means operatively connected with said drive element for effecting reverse movement of said drive element independently of door opening rotation of said shaft, and actuating means for said ratchet means operable by said drive element to release said ratchet means by an initial advance movement of said drive element and adapted to prevent release of said.

ible element connected at one end with said shaft and atthe other end with said reciprocable element, said shaft being rotatable in one direction by opening movement of said doors and in the opposite direction through said flexible element by advance movement of said reciprocable element, means operatively connected with said drive element for effecting reverse movement thereof independently of rotation of said shaft, means for releasably locking said shaft against door opening rotation, and actuating means for said locking means operable by said drive element to release said locking means by an initial advance movement of said drive element and adapted to prevent release of said locking means by said reverse movement of said drive element.

5. In combination with a dump wagon having bottom dump doors, a rotatable winding shaft, flexible means operatively connecting said winding shaft with said bottom dump doors and adapted to rotate said Winding shaft in unwinding direction by force of gravity acting upon said doors, means for releasably locking said winding shaft against unwinding rotation, a cylinder and a piston reciprocably mounted therein, flexible connecting means between said winding shaft and said piston, adapted to rotate said winding shaft in winding direction by movement of said piston in an advance direction, means for selectively applying and releasing fluid pressure at one side of said piston, spring means associated with said piston and counteracting movement thereof by said fluid pressure, and actuating means for said locking means operable by an element reciprocable with said piston and adapted to release said locking means by an initial movement of said piston in said advance direction, and adapted to prevent release of said locking means by movement of said piston in the opposite direc 1 tion.

6. In combination with a dump wagon having bottom dump doors, a rotatable Winding shaft, flexible means operatively connecting said winding shaft with said bottom dump doors and adapted to: rotate said winding shaft in unwinding direction by force of gravity acting upon said doors, means for releasably locking said winding shaft against unwinding rotation, a cylinder and a piston reciprocably mounted therein, means for selectively applying and releasing fluid pressure at one side of said piston, spring means dissociated with said piston and counteracting advance movement thereof under said fluid pressure, flexible connecting means between said winding shaft and said piston, adapted to rotate said winding shaft in winding direction under the action of fluid pressure upon said piston, and actuating means for said locking means operable by an element reciprocable with said piston and adapted to release said locking means by an initial movement of said piston under fluid pressure and adapted to prevent release of said locking means by movement of said piston under the action of said spring means.

'7. In a door operating mechanism, power actuated means adapted to effect closing of the doors and operable to have a first idling movement prior to the closing of the doors and a second idling movement subsequent to the closing of the doors, means for releasably locking the doors in closed position, and actuating means for said locking means operable by said power actuated means and adapted to release said locking means during said first idling movement of said power actuated means, and adapted to prevent release ofsaid locking means during said second idling movement of said power actuated means.

8. In a door operating mechanism, a rotatable door actuating shaft, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to engage said ratchet wheel for holding said shaft against door opening rotation,a reciprocable drive element, lost motion connecting means operable by movement of said drive elementin an advance direction, to effect door closing rotation of said shaft and adapted to permit unrestrained door opening rotation of said shaft after return of said drive element by reverse movement thereof to its starting position, means for effecting said reverse movement of said drive element independently of rotation of said shaft, and mechanism for releasing said pawl from looking engagement with said ratchet wheel, said mechanism comprising a trigger arm engageable with and disengageable from saidv drive element during an initial movement of said drive element in said advance direction, and operatively connected with said pawl carryingarm so as to release said pawl during said initial advance movement of said drive element.

9. In a, door operating mechanism, a shaft rotatable in door opening and door closing directions, a reciprocable element, means connecting said reciprocable element with said shaft for door closing rotation of the latter by advance movement of said reciprocable element and adapted to permit idling return movement of said reciprocable element, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to engage said ratchet wheel for holding said shaft against door opening rotation, a trigger arm having lost motion connection with said pawl supportingarm and being operable by engagement with said reciprocable element during an initial advance movement of the latter to release said pawl.

10. In a door operating mechanism, a shaft rotatable in door opening and door closing directions, a reciprocable element, means connecting said reciprocable element with said shaft for door closing rotation of the latter by advance movement. of said reciprocable element and adapted to permit idling return movement of said reciprocable element, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to engage said ratchet wheel for holding said shaft against door opening rotation, a trigger arm operatively connected with said pawl supporting arm and operable by engagement with said reciprocable element during an initial advance movement of the latter to'release said pawl and means for moving said trigger arm out of engagement with said reciprocable element after release of said pawl.

11. In a door operating mechanism, a shaft rotatable in door opening and door closing directions, at reciprocable element, means connecting said reciprocable element with said shaft for door closing rotation of the latter by advance movement of said reciprocable element and adapted to permit idling return movement of said reciprocable element, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to engage said ratchet wheel for holding said shaft against door opening rotation, a trigger arm operatively connected with said pawl supporting arm and operable by engagement with said reciprocable element during an initial advance movement of the latter to release said pawl, and an element rotatable with said shaft and adapted to move said trigger arm out of engagement with said reciprocable element by rotation of said shaft in door openingdirection.

12. In a door operating mechanism, a shaft rotatable in door-opening and door closing directions, a, reciprocable element, means connecting said reciprocable element with said shaft for door closing rotation of the latter by advance movementof said reciprocable element and adapted to permit idling return movement of said reciprocable element, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to enage said ratchet wheel for holding said shaft against door opening rotation, a trigger arm pivotally connected with an extension of said pawl supporting arm and operable by engagement with said reciprocable element during an initial advance movement of the latter to release said pawl, an element rotatable with said shaft andadapted to move said trigger arm backwardly out of engagement with said reciprocable element after release of said pawl, and means including relatively engageable elements associated with said pawl supporting arm and said trigger arm for transmitting said backward movement of said trigger arm to said pawl supporting arm.

13. In a door operating mechanism, a shaft rotatable in door opening and door closing directions, a reciprocable element, means connecting said reciprocable element with said shaft for door closing rotation of the latter by advance movement of said reciprocable element and adapted to permit idling return movement of said reciprocable element, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to engage said ratchet wheel for holding said shaft against door opening rotation, a trigger arm pivoted on a member rigidly connected with said pawl supporting arm, resilient means associated with said trigger arm and said member adapted to urge said trigger arm into the path of said reciprocable element, said trigger arm beingoperable by an initial advance movement of said reciprocable element to release said pawl, and means for moving said trigger arm out of the pathof said reciprocable element after release of said pawl.

14. In adoor operating mechanism, a shaft rotatable in door opening and door closing directions, a reciprocable element, means connecting said reciprocable element with said shaft for door closing rotation of the latter by advance movement of said reciprocable element and adapted to permit idling return movement of said reciprocable element, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to enage said ratchet wheel for holding said shaft against door opening rotation, a, trigger arm pivoted on a member rigidly connected with said pawl supporting arm, resilient means associated with said trigger arm and said member adapted to urge said trigger arm into the path of said reciprocable element, said trigger arm being operable by an initial advance movement of said reciprocable element to release said pawl, an element rotatable with said shaft and adapted'to move said trigger arm backwardly out of the path of said reciprocable element, and means including relatively engageable elements on said trigger arm and said member for transmitting said backward movement of said trigger arm to said pawl supporting arm.

15. In a door operating mechanism, a shaft rotatable in door opening and door closing directions, a chain secured at one end to said shaft and adapted to be wound around said shaft by door opening rotation of the latter, a reciprocable element secured to the other end of said chain,

power means adapted to advance said reciprocable element in a direction to cause pull on said chain, a ratchet wheel secured to said shaft, a swingable arm carrying a pawl adapted to engage said ratchet wheel, a trigger arm operatively connected with said pawl supporting arm, and having a portion in proximity to the portion of said shaft around which said chain is wound, said trigger arm being operable by engagement with said reciprocable element during an initial advance movement of the latter to release said pawl and being disengageable from said reciprocable element by backward movement resulting from contact with said chain during door opening rotation of said shaft, and means including a stop on said trigger arm adapted to transmit said backward movement of said trigger arm to said pawl supporting arm.

16. In a dump wagon having a dump door adapted to open by gravity, releasable means for holding said door in closed position, a drive mechanism including a drive element operable by an initial application of power thereto to advance from a primary to a secondary position, and to advance by a continued application of power thereto from said secondary to a tertiary position, trip means operable by said first advance movement of said drive element to release said holding means, power transmitting means operable by said second advance movement of said drive element to close said door, and means for returning said drive element from its tertiary to its primary position, said power transmitting and trip means being adapted to prevent actuation of said door and holding means by said return movement of said drive element.

17. A door operating system for dump wagons, comprising a door actuating mechanism operable in door opening and door closing directions, locking means for controlling operation of said door actuating mechanism in door opening direction, a, cylinder, a piston within said cylinder, means operable by an initial advance movement of said piston to release said locking means, power transmitting means operable by a continued advance movement of said piston to operate said door actuating mechanism in door closing direction, and manually operable control means for applying fluid pressure to said cylinder at one side of said piston to effect said initial and continued advance movements of said piston, and means for returning said piston to its starting position independently of operation of said door actuating mechanism in door opening direction.

EDWARD R. GREER. EMIL F. NORELIUS. 

